• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.586-597
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• 2004

MAC (Medium Access Control) protocol is necessary for a OLT (Optical Line Termination) to allocate bandwidth to ONUs (Optical Network Units) dynamically in ATM PON (Passive Optical Network) operated in a kind of optical subscriber network having tree topology. The OLT collect information about ONUs and provide all permission with each ONU effectively by means of MAC protocol. Major functions of MAC protocol are composed of the algorism for distributing permission demanded by a ONU dynamically and allocation all permission used in APON properly. Sometimes MAC get to be a element of limiting the whole operation speed and occupy a most frequent operation part of the TC (Transmission Convergence) function module so it have to be designed to guarantee the best quality for each traffic. This paper introduce the way of implementation of a algorism which satisfy all of the upper renditions. This MAC algorism allocate bandwidth according to a number of working ONU and the information of the queue length dynamically and distribute permission for same interval to minimize delay variation of each ONU cell. MAC scheduler for the dynamic bandwidth allocation which is introduced in this paper has look-up table structure that makes programming possible. This structure is very suitable for implementation and operated in high speed because it require very simple and small chip size.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.535-541
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• 2005

This paper proposes a hybrid optical lines composed of single-mode fiber(SMF) and multi-mode fiber(MMF) for gigabit-capable Passive Optical Network(GPON) using a WDM method with a single light source per each channel, and reports the results of transmission performance the proposed lines. The transmission link uses a direct modulated DFB-LD for high speed downstreams at the optical line terminal(OLT) of central office(CO) and a low cost SFP type transceiver for low-speed upstream in optical network unit(ONU). To split or combine the transmission channels, wavelength MUX/DEMUX are used in the optical line section, and MMFs not longer than 1 km are attached to the SMF lines at the ONU side of the WDM-PON links. We have performed the transmission experiment on the downstream of 2.5 Gbit/s, and 1.25 Gbit/s, and the upstream of 1.25 Gbit/s, and 622 Mbit/s which are recommended by ITU-T G.984.2. The transmission margin and feasibility of the proposed links have been tested to be suitable up to 2.5 Gbit/s transmission.

• Korean Journal of Optics and Photonics
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• v.22 no.3
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• pp.122-128
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• 2011

The AWG-filtering effect was investigated on a bidirectional 100-GHz-channel-spacing WDM-PON link using spectrum-sliced and RSOA-amplified light sources for downstream signals and a wavelength reuse technique for upstream signals. Signal performances of three different filtering AWGs, including Gaussian, trapezoidal, and rectangular types, were compared on link transmission with fiber nonlinear effects. As an extinction ratio of a downstream signal varied, the effect for both directional signals was analyzed and optimized. It was found that there was an optimal pass bandwidth of an AWG for the balance between relative intensity noise decrement and cross phase modulation noise increment as the bandwidth got wider.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.12
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• pp.3310-3329
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• 2023

This work designs an eighteen-channel bidirectional Intensity Modulation with Direct Detection (IM/DD) Wavelength Division Multiplexing-Passive Optical Network (WDM-PON) system. The proposed system meets the requirement of the ITU-T 5G fronthaul link suggested design in G-series Recommendations-Supplement 66. The newly designed system, with a 25Gb/s/λ data rate (450Gbps as a system capacity), has been tested and simulated using OptiSystem V.19 software. The system has been evaluated by the BER with respect to variable the optical span and CW laser power. Based on the ITU-T recommendations, the simulation results demonstrate that this system might be used as an F1 and as an Fx 5G fronthaul link for functional split choices starting from options 1 to 7a. These options are required under 25Gbps/λ for each upstream and downstream link direction. Furthermore, the proposed system utilized a bidirectional single-mode optical fiber within short optical spans of up to 10 km. The proposed system is characterized by a low-cost, simple, DSP-free and amplifier-free system with a reasonable system capacity.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.6
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• pp.412-419
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• 2001

In accordance with the PON(passive optical network) could be setup, effective connections with light sources, optical detectors, and optical fibers are the best sensitive points to represent the efficiency of network. Therefore, in this paper we designed and fabricated optical transceiver connection chip that was consisted of channel waveguide, Y-branch, and CWDM on the 2" BK7 glass substrate. This chip can be used for 1.31/1.55${\mu}{\textrm}{m}$ CWDM network and 1.55${\mu}{\textrm}{m}$ region dense WDM network.work.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1207-1215
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• 2004

A Gigabit Ethernet upstream transmission over a WDM-PON employing remotely wavelength-locked Fabry-Perot lasers has been demonstrated. We have successfully demonstrated a WDM transmission of four Gigabit Ethernet channels with 100 GHz channel spacing over 30 km conventional single mode fiber. The measured f-factor was larger than 17.1 dB. We have also investigated the beating noise characteristics of a wavelength-locked Fabry-Perot laser and showed the remotely wavelength-locked Fabry-Perot laser suppresses the intensity noise of the incoherent light injected, which cause a 6.3 dB SNR improvement compared with that of the conventional spectrum-sliced light source.

• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.16-22
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• 2023

Enhanced radio access technologies (RAT) are deployed in Next Generation Convergence Networks by the service providers so as to satisfy the basic requirements of end-users for e.g. QoS. Whenever the available resources are being shared simultaneously and dynamically by multiple users or distribution of allocated channels randomly, the deficiency of spectral resources and dynamic behavior of Network traffic in real time Networking, we may have problem. In order to evaluate the performance of our proposed algorithm, computer simulation has been performed on NS-2 simulator and a comparison with the existing algorithms has been made.

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.6-11
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• 2012

A bidirectional TDM-PON link to support 2.5 Gb/s upstream signals of 256 ONUs was considered for an extended transmission distance of 50 km. The power budget of the link was 58 dB for the upstream signal and a SOA was applied as a link extender which had a 25 dB gain. Receiver sensitivity of the upstream signal was -25 dBm for -30 dBm input power to the SOA. When the input power was -10 dBm, pulse overshooting caused by gain transient of the SOA was maximum at 45% and the signal performance degradation gave a power penalty of 1.55 dB for $10^{-12}$ BER. However the penalties diminished rapidly and became negligible as the input power went below -15 dBm. So this input power dynamic range of up to -15 dBm means that it is not positively necessary to use gain control methods for the next generation TDM-PON systems.

• Information and Communications Magazine
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• v.31 no.8
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• pp.74-83
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• 2014

수동형 광가입자망 (PON: Passive Optical Network) 기술은 가입자의 단말과 국사의 장비를 광섬유로 직접 연결하여 기존의 전화선 및 동축케이블을 이용한 xDSL 및 HFC등에 비해 전송속도가 빠르고 관리가 수월한 인터넷 서비스 제공이 가능한 기술이다. 본고에서는 ITU-T와 IEEE에서 진행중인 차세대 수동형 광가입자망 기술의 국제 표준화 동향에 대하여 알아보고, 관련 기술개발 현황 및 새롭게 부각되는 스마트 광 분배망 기술과 SDN (Software Defined Network) 기반 광가입자망 운용관리 등의 연구분야에 대하여 알아본다.

• Electronics and Telecommunications Trends
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• v.19 no.6 s.90
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• pp.43-54
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• 2004

WDM-PON은 가입자망의 트래픽 병목 현상을 해결하고, 다양한 서비스 품질을 제공하면서 고속화된 데이터 전송을 위해 가입자 당 독립 파장을 할당함으로써 가입자의 요구 대역에 제한을 받지 않으며, 보안성이 보장되는 차세대 WDM 기반 수동형 광가입자망이다. 특히 고성능, 저가인 광소자를 포함한 광모듈의 조기개발이 FTTH 네트워크 초기 시장 및 서비스를 선점하는 척도가 될 것으로 예상된다. 본 논문은 WDM 기반 수동형 광가입자망 동작 방식, 광다중화기 및 역다중화기, 그리고 WDM -PON과 WDM 다중화 기술인WDM/TDM, WDM/SCM, WDM/CDM을 포함한 다양한 광 수동 가입자망 구성 기술을 소개한다.